Recently, personal checks, on which pieces of information such as bank numbers, account numbers and so forth are printed by magnetic ink characters, are widely used for commercial transactions and shopping at stores. Accordingly, readers have been proposed for reading magnetic ink characters printed on personal checks. Such prior readers have a compound structure described as follows: magnetic heads are made to come into contact with magnetic ink characters printed on the surface of a personal check, so that the magnetic ink characters can be read, and at the same time, printing is conducted on the reverse side of the personal check by a printing head according to the content of reading. Such a prior art reader and problems encountered with it are further described in the detailed description below.